الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The reaction of three cultivars of sunflower i.e. Giza 35, Sakha 53 and 162 and soybean i.e. Giza 111, Giza35 and Giza11 to root-knot nematode, M. incognita was evaluated under greenhouse conditions. Results revealed that sunflower and soybean cultivars were remarkably affected by M. incognita infection in terms of plant length and total plant fresh weight. Cultivar Sakha 53 recorded the highest percentage of reduction in sunflower plant fresh weight (34.25%) followed by 162 (33.43%) then Giza 35 (21.46%) cultivars. According to the reproduction factor and root gall index, cultivars of sunflower Giza 35 and Sakha 53 were rated as susceptible hosts whereas cv.162 was rated as highly susceptible to nematode infection. On the other hand, soybean cultivar Giza 35 was highly affected and exhibited the highest percentage reduction values in plant length (36.6%). Nevertheless, highest reduction in plant fresh weight (69.1%) was recorded with Giza 35. Hence, cultivars of soybean Giza 35 and Giza 111 were rated as susceptible hosts whereas Giza 11 was rated as tolerant host to nematode infection. In the present investigation, the six screened cultivars of canola were planted in winter, October 2017, when the temperature and nematode activity are decreased. Hence, all cultivars were found as non-host to the target nematode. Therefore, it could be recommended to be used in crop rotation and as green manure due to the presence of metabolites glucosinolates. The effectiveness of two microbial agents namely cyanobacterium, Spirulina platensis, and yeast, Saccharomyces cerevisiae and two organic amendments namely yeast extract and molasses, applied singly or in integration at two concentrations (50 and 100 ppm) on egg hatching and juveniles survival of M. incognita was studied in vitro and in vivo. Irrespective of tested concentrations almost all treatments were found to cause detectable inhibition in hatching rate with various degrees compared to the control. As the concentration of individual agents increase a greater inhibition in egg hatching and nematode mortality was recovered. The highest percentage of egg hatching inhibition was recorded with molasses (37.75%) and cyanobacterium (30.06%) at 100 ppm. Nevertheless, the percentage of egg hatching inhibition was not proportionally correlated with the concentration of combined application at 100 ppm. Hence, the percentage of egg hatching inhibition was obviously increased with the dual and triple application of various treatments at 50 ppm concentration compared to individual treatments. The highest percentage of increase in egg hatch was significantly recorded with the combination of cyanobacterium + yeast + molasses (41.68%) followed by yeast extract + molasses (39.55%) then cyanobacterium + yeast extract (38.49%). The effectiveness of four bio-agents, cyanobacterium, yeast, molasses and yeast extract were studied individually against M. incognita infecting sunflower cv. Sakha53 compared with oxamyl and control (untreated infected plants) under greenhouse conditions. Plant parameters in terms of plant fresh weight were obviously improved with the application of yeast and cyanobacterium. However, oxamyl showed the best augmentation in plant length with percentage of increase amounted to 52.6%. Nematode parameters in terms of the number of galls and juveniles /pot were greatly decreased with the application of S. platensis and S. cerevisiae as well as organic amendments. Yeast, S. cerevesiae had a beneficial effect on suppressing the nematode population in the soil giving the reduction percentage equal 40.15. Number of galls were significantly (p≤0.05) reduced by all screening treatments in a range of 46.38 to 68.35%. Yeast extract (68.35%) performed the best in suppressing gall formation followed by S. platensis (63.03%). Chemical constituents i.e. nitrogen and phosphorus were significantly decreased as a result of nematode infection. However, untreated plants showed a significant increase in potassium concentration. The potential of screened bio-agents to induce nitrogen and phosphorus were performed with cyanobacterium and yeast. Moreover, the potential of such bio-agents, cyanobacterium, yeast, molasses and yeast extract was studied individually and in combination against Meloidogyne incognita infecting soybean cv. Giza 53 compared with oxamyl and control (untreated infected plants) under greenhouse conditions. Results showed that M. incognita infection caused a significant decrement in plant growth parameters with reduction percentage in plant length and shoot weight reached 30.19 and 53.54%, respectively. Among single application yeast extract showed the best augmentation in total plant fresh weight and shoot weight with percentage of increase amounted to 132.61 and 146.30, respectively. Molasses and yeast (84.8; 118.5%) (69.6; 81.5%) ranked the next in improving such parameters, respectively. Apparently triple applications gave better results than did single or dual applications. Hence, in dual applications a synergistic impact on soybean growth in terms of fresh shoot weight and total plant fresh weight was induced with various degrees as compared with a single application. Cyanobacterium + molasses were the most effective in improving soybeans shoot weight and total fresh weight with percentage amounted to 150 and 170.4%, respectively. Yeast integrated with molasses or cyanobacterium ranked the next in improving such parameters. Triple application including cyanobacterium + yeast + molasses showed the best augmentation in plant length (14.8%), shoot weight (258.7%) and total plant weight (261.1%). All treatments resulted in a remarkable suppression in a number of galls and nematode population densities in soil and root. The highest percentages of reduction in nematode population in soil, number of females and developmental stages were recovered with oxamyl (100%). Among single bio- control agents, yeast (55.0%) performed the best in suppressing the total population. In dual treatments, nematode population in soil and root were significantly (p≤0.05) suppressed, by cyanobacterium + molasses (73.9%). At triple application consisting of cyanobacterium + yeast + molasses (89.3%) surpassed other treatments and significantly (p≤0.05) the reduced nematode population. On the other hand, the number of galls was significantly (p≤0.05) reduced by all screening treatments in a range of 61.5 to 100%. Chemical constituents (chlorophyll A, B and NPK) in dried leaves of soybean were significantly decreased as a result of nematode infection. Chlorophyll content A and B as well as N, P, K were significantly induced by screened bioagents with different degrees. The current study revealed the susceptibility of screened sunflower and soybean cultivars to root-knot nematode, M. incognita infection with different degrees. Application of both cyanobacterium, S. platensis and yeast, S. cerevisiae in integration with molasses or yeast extract mitigated the deleterious impact of root-knot nematode infection on susceptible cultivars, as well as induced plant growth parameters and altered chemical constituents, therefore, it could be recommended as ecofriendly alternatives of nematicides and chemical fertilizers. In addition, the present study revealed that screened canola cultivars were considered as poor or non-hosts to the target nematode, hence, it could be recommended for the biomanagement of M. incognita in organic farming.